Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Walter B. Knighton. Includes bibliographical references (leaves 131-145).

Thesis (I.M.E.S.)--Baylor University, 2009. / Includes bibliographical references (p. 107-118).

The ability to quickly and efficiently locate concealed human remains is crucial in forensic investigations and when locating disaster victims. On occasions when human remains are recovered, correctly assigning a postmortem interval (PMI) may become necessary to corroborate statements or make an identification. While Human Remains Detection canines (HRD canines) provide rapid and sensitive searches, the mechanisms behind their sense of smell remain poorly understood. Over the past ten years, volatile organic compounds (VOCs) have been investigated in an effort to address questions concerning PMI, optimization of training aids, and portable 'sniffing' devices. The approaches taken for investigating VOCs emitted from decomposing tissues buried or otherwise have been diverse. They range from burying entire human bodies and sampling the above-ground volatiles using triple-sorbent traps (TSTs) to isolating small amounts of tissue into glass vials whereby the volatiles are sampled by Solid Phase Microextraction (SPME). The resulting studies have led to large quantities of data that are difficult to interpret and compare between studies. Furthermore, the restrictions surrounding access to human remains have caused many studies to use other animals, (pigs, chickens, cows, and deer) in particular the domestic pig, due to its similarities in hair coverage and tissue ratios. There have been several studies that attempt to address the effects that burial has on the resulting VOCs. However, the addition of a complex matrix to a process that already has many variables has caused difficulty in data interpretation. The purpose of this study was to identify how freezing and the presence of soil affect the VOC profiles of various tissue types (blood, bone, fat, small intestine, muscle, and skin) obtained over six weeks of decomposition. In order to accomplish this, the study was performed in three parts. The first part used fresh pig samples obtained only hours after euthanization, the second part utilized tissues from the same areas of the pig after the samples had been frozen for 6 weeks and the third part combined soil with three of the tissue types (blood, bone, muscle). SPME was employed at room temperature using a 65 µm PDMS/DVB coated fiber as the adsorbent material to extract the VOCs from the headspace. The use of SPME as the extraction method allowed for direct desorption and subsequent analysis into the injection port of the GC/MS. User-defined integration parameters were applied to each resulting chromatogram in an effort to identify what impact, if any, freezing and soil had on the resulting VOC profiles. The results obtained in this study suggest that the freezing and thawing of tissue samples have varying effects on the resulting chromatograms based on the complexity of the tissue-type. This implies that prolonged use and storage of some, commonly utilized, training aids may not be providing the most reliable scent profile for the HRD canines. Results obtained from the soil study were complex, but several overall trends were observed in the release and production of different compound classes. Comparisons to previous studies using similar extraction procedures demonstrate the need for a standardized protocol for future decomposition studies.

M.Tech. (Chemical Engineering) / Increasing pressure on industry from national and international communities for more environmentally friendly operations has generated a drive towards the use of ‘green’ absorbents in the removal of volatile organic compounds from contaminated air streams. The objective of this work was to investigate the use of ester solvents, especially biodiesel esters, as suitable ‘green’ scrubbing solvents for the absorption of volatile organic compounds (VOCs) from gaseous waste streams. The objective was accomplished by investigating the nature of molecular interactions between ester solvents and various families of VOC solvents, and by studying the effect of temperature on absorption, through the analysis of infinite dilution activity coefficients. Activity coefficients were computed with a Microsoft Excel generated spread sheet using Modified UNIFAC Dortmund (1987) as a thermodynamic predictive model. Results show that non-polar solutes are more soluble in long chain ester solvents whilst polar solutes absorb easier in short chain ester solvents. The solubility of non-polar solutes decreases with increasing ester solvent unsaturation, whilst the opposite is true for polar solutes in esters. Short chain length non-polar solutes are more soluble than long chain length non-polar solutes in ester solvents, whilst the opposite trend occurs for polar solutes in ester solvents. An increase in branching of polar solutes results in the solute behaving more like a non-polar solute. Unfortunately UNIFAC models fail to account for functional group proximity effects, which may result in inaccurate results for systems involving highly branched solutes. However given that the purpose of this study was only to establish trends for generating an understanding of molecular interactions between the solutes and the solvent, it was acceptable to assume that these inaccuracies would be minor for the intended purpose. It was found that activity coefficients of ester/ solute interactions generally tend towards ideality with increasing temperature with the exception of alkanes and the nitrogen based VOCs, as well as tetrahydrofuran and tetrahydropyran, methacrolein and organic acid/ unsaturated ester interactions. In the case of the alkanes, tetrahydrofuran and tetrahydropyran, high-temperature absorption is preferred whilst for methacrolein lower temperature absorption is preferred. It was concluded that ester solvents ,especially biodiesel esters, are well suited for the removal of non-polar to moderately polar VOC solutes from waste gas streams due to the favourably low activity coefficients obtained for these ester/ solute interactions. The results presented in this report are comprehensive and can assist in making informed decisions in using biodiesel as a scrubbing solvent.

No description available.

In certain European countries and the United States of America, canines have been successfully used in human scent identification. There is however, limited scientific knowledge on the composition of human scent and the detection mechanism that produces an alert from canines. This lack of information has resulted in successful legal challenges to human scent evidence in the courts of law. The main objective of this research was to utilize science to validate the current practices of using human scent evidence in criminal cases. The goals of this study were to utilize Headspace Solid Phase Micro Extraction Gas Chromatography Mass Spectrometry (HS-SPME-GC/MS) to determine the optimum collection and storage conditions for human scent samples, to investigate whether the amount of DNA deposited upon contact with an object affects the alerts produced by human scent identification canines, and to create a prototype pseudo human scent which could be used for training purposes. Hand odor samples which were collected on different sorbent materials and exposed to various environmental conditions showed that human scent samples should be stored without prolonged exposure to UVA/UVB light to allow minimal changes to the overall scent profile. Various methods of collecting human scent from objects were also investigated and it was determined that passive collection methods yields ten times more VOCs by mass than active collection methods. Through the use of polymerase chain reaction (PCR) no correlation was found between the amount of DNA that was deposited upon contact with an object and the alerts that were produced by human scent identification canines. Preliminary studies conducted to create a prototype pseudo human scent showed that it is possible to produce fractions of a human scent sample which can be presented to the canines to determine whether specific fractions or the entire sample is needed to produce alerts by the human scent identification canines.

Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2010. / Chemistry / unrestricted

No description available.

My research focuses on the development of a novel method for the fast detection of aflatoxin-producing fungi from the volatile organic compounds that they produce. Aflatoxins have received great attention because of their demonstrated potent carcinogenic effect in susceptible laboratory animals and their acute toxicological effects in humans. Traditional detection and quantification techniques are considered time-consuming, high cost, and require technical professionals. The `odor' or so called volatile metabolites released by a fungus is the key for fast detection. Several researchers have reported that diverse fungi species have unique volatile metabolite patterns. This study focuses on answering several questions: Is it possible to discriminate aflatoxins-producing fungi from other fungi based on volatile metabolites? What are the key discriminating biomarkers related to each fungus? Does the growth environment have an effect on the production of volatile metabolites? What chemicals are consistently emitted by a fungus under varied conditions? To answer these questions, one toxigenic and one nontoxigenic A. flavus isolate were studied to evaluate the microbial volatile organic compound (MVOC) profiles. The results described in chapter two of this dissertation indicate that MVOC production is time-dependent and that aflatoxigenic and non-aflatoxigenic strains have different MVOC expression patterns. Chapter three describes the effects of experimental parameters on fungal volatile metabolites. The identity and quantity of MVOCs can be affected by many factors including SPME fiber type, fungal growth media, and growth temperature. A CAR/PDMS coated fiber performed better than the other SPME fibers by collecting a larger variety and quantity of MVOCs. Fungi grown on the chemical defined liquid media produced much larger quantities of MVOCs compared to the other media. The highest MVOC production results were found at 30 degrees Celsius. The fungi discrimination study was extended in chapter four by including 3 toxigenic and 3 non-toxigenic isolates using multivariate analysis. The results indicate that volatile patterns vary even at the fungal isolate level and that discrimination of aflatoxin-producing fungi from non-toxigenic fungi is possible.

Many models for predicting volatile organic compounds (VOC) emissions from latex paints have been developed. Earlier models were developed for solvent-borne paints, particularly since these paints evaporate rapidly and can be modeled with simple decay models. However, paint has changed in the past fifty years, and a transition has been made towards water-borne paints. These paints were introduced for indoor applications because they lacked the health hazards and odors of their solvent-borne counterparts. These paints also have organic modifiers, therefore it is very important to predict how these modifiers evaporate from the coated material. New mechanistic models that can predict slow emitting VOCs over long periods of time are not available. An improved ability to predict VOC emissions from latex paints could lead to improved understanding, better policy-making and promotion of environmental regulations that benefit both the consumer and producers of architectural coatings. This research improves on existing models used to estimate VOC emissions off-gassed from latex paints. The developed two layer model (2LM) has a layer for paint and substrate material, and accounts for mass transfer at the paint layer, and diffusion transport between paint and material layers. The model provides a semi-mechanistic way to predict paint drying and VOC emissions from coatings on a variety of substrates. The model only requires the estimation of one parameter (the paint layer diffusion coefficient), unlike other models available that require multiple parameter estimations. This model is robust in the sense that it could be used to predict VOC emissions from paint, as well as predicting the variation of the internal VOC distribution on both paint and material layers with time. The model was tested and validated with empirical data collected from previous controlled chamber experiments, and also with data collected from short evaporation experiments. Critical paint components like polymer and pigment composition and its relation to VOC fate and transport after paint application, both initially and over long periods of time, were explored. Modeling results indicated that the diffusion coefficient of 2,2,4-trimethyl-1,3-pentadediol monoisobutyrate (TMPD-MIB) in the paint layer does not depend on the thickness of the wet paint film, but it depends on the pigment volume concentration (PVC) of the paint. Additionally, a constant diffusion coefficient used in the 2LM was successful for modeling emissions of TMPD-MIB from low pigment volume concentration (LPVC) paints, but it failed to capture the physical mechanisms of the drying film for high pigment volume concentration (HPVC) paints. A major finding from this research was that a detailed gas phase analysis of mass transport for TMPD-MIB would have negligible effects on the predicted overall evaporation rate. Therefore, the entire wet and dry emissions processes are likely dominated by diffusion processes. / text